Proton implantation-induced intermixing of InAs quantum dots ͑QDs͒ capped with InP, GaInAsP, and InP and InGaAs layers grown by metal-organic chemical vapor deposition is investigated. The samples are annealed at 750, 800, 850, and 900°C for 30 s and thermal stability of the QDs is studied. The optimum annealing temperature is around 800°C which gives maximum implantation-induced energy shift. The QDs capped with InP layers show the highest implantation-induced energy shift due to strong group V interdiffusion whereas the QDs grown on and capped with GaInAsP layers show the least implantation-induced energy shift due to weak group V and group III interdiffusion. The QDs capped with InP and InGaAs layers show intermediate implantation-induced energy shift and are less thermally stable compared to the QDs grown on and capped with GaInAsP layers. The QDs capped with InP layers show enhanced photoluminescence ͑PL͒ intensity when implanted with lower proton dose ͑less than 5 ϫ 10 14 ions/ cm 2 ͒. On the other hand higher proton dose ͑more than 1 ϫ 10 14 ions/ cm 2 ͒ reduces the PL linewidth in all samples.

We report the experimental results of tuning the emission wavelength of InAs∕InP quantum dots (QDs) by varying either the GaAs interlayer thickness or the indium composition of the InxGa1−xAs interlayer. The InAs QDs are grown on lattice-matched GaInAsP or InP buffers and are capped with an InP layer. As∕P exchange is prominent when the QDs are grown on an InP buffer. A model is developed which considers the As∕P exchange, gallium interdiffusion, strain, and barrier height. Our theoretical and experimental results show that gallium interdiffusion and the As∕P exchange reaction are mainly responsible for the observed shifts in the QD emission wavelength. The model shows that gallium interdiffusion from the interlayer to the InAs QDs grown on a GaInAsP buffer can be utilized to selectively tune the InAs QD emission wavelength over a wide range.

We report on the growth of InAs quantum dots (QDs) on GaInAsP and InP buffers by metal-organic chemical vapour deposition on InP(100) substrates. Indium segregation and the AsP exchange reaction affect the QD nucleation and composition. The AsP exchange reaction has a more pronounced effect on the QDs grown on the InP buffer than on those grown on the GaInAsP buffer. A very thin (0.6 nm) GaAs interlayer grown between the buffer layer and the InAs QD layer consumes segregated indium and minimizes the As/P exchange reaction. Wavelength tuning from 1450 to 1750 nm covering the technologically important 1550 nm wavelength is also achieved for the InAs QDs grown with the thin GaAs interlayer.

Impurity-free disordering ͑IFD͒ of the InAs quantum dots ͑QDs͒ capped with either an InP layer or an InGaAs/ InP bilayer is studied. The samples are coated with a SiO 2 or TiO 2 dielectric layer followed by rapid thermal annealing at 700, 750, 800, and 850°C for 30 s. A large differential energy shift of 157 meV is induced by SiO 2 in the QDs capped with an InGaAs/ InP bilayer. Contrary to the reported results on the suppression of intermixing of GaAs based QDs by TiO 2 , the authors find that intermixing of InAs/ InP QDs is promoted by TiO 2. X-ray photoelectron spectroscopy depth profiles show that both In and P outdiffuse to a TiO 2 layer whereas Ga, In, and P outdiffuse to a SiO 2 layer leading to different degrees of intermixing. The results indicate that a group V interstitial diffusion mechanism might be responsible for IFD of InAs/ InP QDs.

The effect of high temperature annealing of the InAs∕InP quantum dots (QDs) containing a thin GaAs interlayer is investigated. The QDs are rapid thermally annealed at 750, 800, 850, and 900°C for 30s. The QDs with the GaAs interlayer show good thermal stability up to 850°C as well as enhanced integrated photoluminescence (PL) intensity and reduced PL linewidth. The effect of high energy (450keV) phosphorous ion implantation at room temperature with doses of 5×1011–5×1013ions∕cm2 with subsequent high temperature (750–850°C) rapid thermal annealing is also studied. A large implantation-induced energy shift of up to 309meV (400nm) is observed. The implanted samples annealed at 850°C show reduced PL linewidth and enhanced integrated PL intensity compared to the implanted samples annealed at 750°C.